Vibration noise with no power?

[pnishr]

I've had my battery disconnected for about a week while i do some work on the car. This weekend while working, i heard some kind of vibration from the car. sounded like in the engine bay, but i don't know. all the posts i found on here said something about the ECU, but mostly in reference to a 1g. I'm a 96. Is it still possibly something with the ECU. Would that make a weird, almost cell-phone sounding vibration noise? How does this happen with no power. like i said, the battery has been off for over a week. OK, hopefully somebody knows. Thanks.

 

[pnishr]

I've had my battery disconnected for about a week while i do some work on the car. This weekend while working, i heard some kind of vibration from the car. sounded like in the engine bay, but i don't know. all the posts i found on here said something about the ECU, but mostly in reference to a 1g. I'm a 96. Is it still possibly something with the ECU. Would that make a weird, almost cell-phone sounding vibration noise? How does this happen with no power. like i said, the battery has been off for over a week. OK, hopefully somebody knows. Thanks.

Since nobody knew the answer, i thought I'd post it now that I've found it, in order to better serve anybody that ever hears it. It was: the little one-way valve that sits between the gas tank fumes hard-line, and the hose that goes to the Charcoal evaporative fumes canister. since its hot here in Texas, the gas was heating and causing pressure in the tank. when it built up enough to push past the valve, it made a vibrating "trumpeting" noise. I happened to have my hand on it pulling out the canister when it did it. So, if you have used the search button because you had this problem, now you have the answer.